In superjunction semiconductor devices complementary doped first and second semiconductor regions alternate along at least one horizontal direction in a drift layer. The doping concentrations in the first and second semiconductor regions are adjusted to each other such that even at comparatively high dopant concentrations in the superjunction structure a portion of the drift layer including the superjunction structure can be completely depleted in a blocking state of the semiconductor device. A semiconductor device with high dopant concentration in portions of the drift layer shows comparatively low on-state resistance.
Superjunction structures may be formed by etching trenches into a semiconductor layer of a first conductivity type and filling the trenches with semiconductor material of the complementary second conductivity type. After formation of the superjunction structure, a superstructure including transistor cells may be formed in a semiconductor layer above the superjunction structure. For aligning the transistor cells to the superjunction structure, an alignment mark is formed before or after the formation of the superjunction structure.
It is desirable to align a superstructure to a foundation, which includes a superjunction structure, in a reliable and economic way.